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Significant Figures Rounder

Significant Figures Rounder is part of Toolspire and is ready as soon as this page loads. Leading zeros before the first non-zero digit are not significant. The count starts at the first non-zero digit. Zero itself stays 0.

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What you can do here

Leading zeros are skipped

The first significant digit of 0.012 is 1, not 0.

Large numbers use scientific notation

So trailing zeros are not ambiguous.

A cap of 10

More digits than the input usefully has is a different request from a school rounding.

The sequence

How to use the Significant Figures Rounder

  1. 1

    Count from the first non-zero digit

    Three significant figures in 1.2345 are 1, 2 and 3.

  2. 2

    Check 1.23

    The following digit is 4, so 1.23 does not round up.

  3. 3

    Try 0.012345 with 2 figures

    You should see 0.012, not 0.01 from a decimal-place rule.

Worth knowing

  • Significant Figures Rounder on Toolspire: 1.2345 to 3 significant figures is 1.23.
  • 0.012345 to 2 significant figures is 0.012. The zeros in front do not count.
  • 12345 to 3 significant figures is 1.23 × 10^4, because 12300 would hide how many zeros are significant.
  • The count must be an integer from 1 to 10.

Significant figures are not decimal places

Decimal places count digits after the point. Significant figures count from the first non-zero digit. 0.012345 to two significant figures is 0.012, which has three digits after the point and two significant digits. 1.2345 to three significant figures is 1.23. A large integer such as 12345 to three figures is written 1.23 × 10^4 so the rounded zeros are not mistaken for measured zeros.

FAQ

Questions about Significant Figures Rounder

Where does Significant Figures Rounder run?

Significant Figures Rounder runs in this tab on Toolspire. What you type or drop in is not sent to us and is not stored on a server.

What is 1.2345 to three significant figures?

1.23.

What is 0.012345 to two significant figures?

0.012.

Why is 12345 to three figures not 12300?

Because 12300 can be read as having three, four or five significant figures. Scientific notation makes the three digits explicit.

Do leading zeros count?

No. They only place the decimal point.

Keep going

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